This invention relates to a color printing apparatus and, more particularly, to a thermal transfer type printing apparatus using a thermal head.
Color printing apparatuses usually are provided for business purposes and are large in scale. Recently thermal transfer types have become available. A thermal transfer type color printing apparatus is small in size, requires no substantial maintenance and has high reliability. For these reasons, they are used for various apparatuses such as color electrographic apparatuses. In the prior art thermal transfer type color printing apparatus, however, different printing operations for four different colors, i.e., black, cyan, magenta and yellow, must always be done successively in a single printing section. Therefore, unnecessary printing operations are performed for monochromatic prints. This not only means that the printing speed is reduced but also the efficiency of ink ribbon use is also reduced since unused portions of the ink ribbon are discharged.
Further, monochromatic printing inevitably requires increased resolution, that is, a thermal head having a large number of bits must be used. Therefore, when a thermal head for color printing is driven, signal processing involving a number of bits must be done a number of times. This complicates the circuitry and increases the cost of the thermal head.